Entity is an object-relational mapping tool for the D programming
language. Referring to the design idea of JPA. support PostgreSQL
/ MySQL / SQLite.
## Support databases
PostgreSQL 9.0+
MySQL 5.1+
SQLite 3.7.11+
## Depends
database
## Simple code
import entity;
@Table("user")
class User : Entity
{
@PrimaryKey
@AutoIncrement
int id;
string name;
double money;
string email;
bool status;
}
void main()
{
DatabaseOption options = new
DatabaseOption("mysql://root:123456@localhost:3306/huntblog?charset=utf-8");
EntityManagerFactory entityManagerFactory =
Persistence.createEntityManagerFactory("default", options);
EntityManager em = entityManagerFactory.createEntityManager();
// begin transaction
em.getTransaction().begin();
// define your database existing row id in here
int id = 10;
auto user = em.find!User(id);
log("User name is: ", user.name);
// commit transaction
em.getTransaction().commit();
em.close();
entityManagerFactory.close();
}
## Insert row
auto user = new User();
user.name = "Brian";
user.email = "br...@huntlabs.cn";
user.money = 99.9;
// insert user
em.persist(user);
log("User id is: ", user.id);
## Delete row
int n = em.remove!User(id);
log("The member of users deleted is: ", n);
## Update row
auto user = em.find!User(id);
log("User name is: ", user.name);
user.name = "zoujiaqing";
em.merge!User(user);
log("The number of users updated is: ", n);
## Use CriteriaQuery to find
// create CriteriaBuilder object from em
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery!User criteriaQuery = builder.createQuery!User;
Root!User root = criteriaQuery.from();
Predicate p1 = builder.equal(root.User.id, id);
TypedQuery!User typedQuery =
em.createQuery(criteriaQuery.select(root).where(p1));
auto user = cast(User)(typedQuery.getSingleResult());
log("User name is: ", user.name);
## Use CriteriaQuery to Multi-condition find
// create CriteriaBuilder object from em
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery!User criteriaQuery = builder.createQuery!User;
Root!User root = criteriaQuery.from();
Predicate p1 = builder.lt(root.User.id, 1000); // User id is
less than 1000.
Predicate p2 = builder.gt(root.User.money, 0); // User money
is greater than 0.
Predicate p3 = builder.like(root.User.name, "z%"); // User
name prefix is z.
TypedQuery!User typedQuery =
em.createQuery(criteriaQuery.select(root).where(builder.and(p1,
p2), p3));
User[] users typedQuery.getResultList();
log("The number of users found is: ", users.length);
## Links
http://code.dlang.org/packages/entity
https://github.com/huntlabs/entity
